Don't count the ATI Radeon out.
I use a 3DfX 5500 on my main computer because it has excellent Windows 2000 drivers. However, when I want to run my computer at 1600x1200 res and 32bit color, I use the radeon. It gives about 28fps on the ground at a typical airport in fighter, and approx 37fps in flight at 1600x1200 res and 32 bit color. I only use the radeon in Win98, the Win2000 drivers really are lousy on that video card at this point.
I can assure you that at 1600x1200 res and 32 bit color, the radeon leaves the 5500 behind in the dust.
I bought my Radeon at Best Buy for $199 and then received $50 off that price with a rebate card. If you want really high res for a decent price AND you use Win98, consider the radeon.